The present invention relates to a method and apparatus for monitoring permeation of hydrogen from a material, for example from steel bodies such as pipelines and the like, which is useful for example in detecting corrosion in a timely manner.
The effect of hydrogen permeation on steel is widely documented. Atomic hydrogen can combine with impurities in steel or with other hydrogen atoms in steel to cause serious degradation of the physical properties of the steel. It is of course desirable to actually quantify this hydrogen permeation activity in an industrial environment. For example, hydrogen permeation activity could be used to indicate the effectiveness of a corrosion control program or the need for corrosion servicing.
U.S. Pat. Nos. 4,065,373 to Martin et al., and 4,221,651 to Mansfeld et al. describe varying types of hydrogen monitoring devices. Common problems experienced with these devices include the use of certain types of electrolyte which themselves are corrosive, the need for palladium membranes and the like to be positioned on the material to be monitored, susceptibility to thermal expansion and loss of sensitivity, and limited useful monitoring lifetimes. Further, these devices may be temperature limited due to the possibility for pressure buildup and the like above certain temperatures.
In light of the foregoing, it is clear that the need remains for a device which can actually monitor hydrogen permeation without using corrosive materials, protective membranes and the like, and without experiencing loss of sensitivity due to thermal expansion, limited lifetime and limited environments of use.
It is therefore the primary object of the present invention to provide a method and apparatus for monitoring hydrogen permeation which does not expose the material being monitored to corrosive materials.
It is a further object of the present invention to provide a method and apparatus which do not require additional protective membranes for the material being monitored.
It is a still further object of the present invention to provide a method and apparatus which does not experience significant loss in sensitivity due to expansion and the like.
It is another object of the present invention to provide an apparatus for monitoring as described which does not have an unduly limited lifetime, and which does not need an external power source.
It is still another object of the present invention to provide a method and apparatus which are not subject to overly restrictive temperature limitations.
Other objects and advantages of the present invention will become apparent hereinbelow.